Giant enhancement of emission intensity by using microcavity

We propose theoretically a tunable circular Bragg microcavity to enhance the intensity of the emission band of interest in rare-earth-doped materials and to suppress the unwanted emission bands which produce noise and diminish the efficiency of the emission of interest. The surrounding of the microcavity comprises of alternating layers of high-index and low-index materials. The luminescent ions such as neodymium Nd3+ having different emission bands in different host materials are placed in the microcavity, and single emission band with stronger intensity can be observed, and other emission bands are suppressed. The wavelength of the single emission peak can be changed from one wavelength to other wavelengths by varying the refractive index, radius of the microcavity and thus modifying the local density of states of the microcavity. The fluorescence branching ratio of emission band of interest can be enhanced from 10% to 100% due to suppression of the unwanted emission bands.